# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Global max pooling 3D layer."""
# pylint: disable=g-classes-have-attributes,g-direct-tensorflow-import

from keras import backend
from keras.layers.pooling.base_global_pooling3d import GlobalPooling3D

from tensorflow.python.util.tf_export import keras_export


@keras_export('keras.layers.GlobalMaxPool3D', 'keras.layers.GlobalMaxPooling3D')
class GlobalMaxPooling3D(GlobalPooling3D):
  """Global Max pooling operation for 3D data.

  Args:
    data_format: A string,
      one of `channels_last` (default) or `channels_first`.
      The ordering of the dimensions in the inputs.
      `channels_last` corresponds to inputs with shape
      `(batch, spatial_dim1, spatial_dim2, spatial_dim3, channels)`
      while `channels_first` corresponds to inputs with shape
      `(batch, channels, spatial_dim1, spatial_dim2, spatial_dim3)`.
      It defaults to the `image_data_format` value found in your
      Keras config file at `~/.keras/keras.json`.
      If you never set it, then it will be "channels_last".
    keepdims: A boolean, whether to keep the spatial dimensions or not.
      If `keepdims` is `False` (default), the rank of the tensor is reduced
      for spatial dimensions.
      If `keepdims` is `True`, the spatial dimensions are retained with
      length 1.
      The behavior is the same as for `tf.reduce_max` or `np.max`.

  Input shape:
    - If `data_format='channels_last'`:
      5D tensor with shape:
      `(batch_size, spatial_dim1, spatial_dim2, spatial_dim3, channels)`
    - If `data_format='channels_first'`:
      5D tensor with shape:
      `(batch_size, channels, spatial_dim1, spatial_dim2, spatial_dim3)`

  Output shape:
    - If `keepdims`=False:
      2D tensor with shape `(batch_size, channels)`.
    - If `keepdims`=True:
      - If `data_format='channels_last'`:
        5D tensor with shape `(batch_size, 1, 1, 1, channels)`
      - If `data_format='channels_first'`:
        5D tensor with shape `(batch_size, channels, 1, 1, 1)`
  """

  def call(self, inputs):
    if self.data_format == 'channels_last':
      return backend.max(inputs, axis=[1, 2, 3], keepdims=self.keepdims)
    else:
      return backend.max(inputs, axis=[2, 3, 4], keepdims=self.keepdims)


# Alias

GlobalMaxPool3D = GlobalMaxPooling3D
